A fuel cell generates electric power by a chemical reaction between hydrogen as fuel and air containing oxygen as oxidant. The fuel cell generates heat with the generation of electric power. When the temperature of the fuel cell rises outside a predetermined temperature range, water evaporates and a dry state occurs, and the power generation performance degrades thereby. Thus, to prevent the overheating of the fuel cell, the control that increases a lower limit voltage with the increase in the temperature of the coolant of the fuel cell to reduce heat generation may be performed. When the lower limit voltage is increased, the output is easily limited because of the characteristics of the fuel cell. There has been various suggestions on the setting of the lower limit voltage as disclosed in, for example, International Publication No, 2008/146928, and Japanese Patent Application Publication Nos. 2009-158397 and 2008-300299.